1. Field of the Invention
This invention pertains to a system and process for making synthetic wood products, such as building materials, including roof shingles, siding, floor tiles, paneling, moldings, structural components, steps, door and window sills and sashes; house and garden items, such as planters, flower pots, landscape tiles, decking, outdoor furniture, fencing, and playground equipment; farm and ranch items, including pasture fencing, posts and barn components; and marine items, for example, decking, bulkheads and pilings, through a process which combines certain wood scrap material, such as cedar fiber waste, and plastic waste materials, such as high density polyethylene, low density polyethylene, polypropylene and mixtures thereof, and equivalent materials.
The starting wood and plastic materials are identified, processed, mixed, and then formed into building material products through use of an extruder and subsequent rolling processes to produce products which have advantages over natural wood and over other synthetic materials, such that products of the present invention are ordinarily less expensive; have excellent insulating properties; are highly resistant to insect infestation, rotting, splitting, cracking, warping, thermal expansion or absorption of moisture; can be easily shaped and machined; and, in many cases, have superior structural integrity.
2. Needs to Which the Present Invention is Directed
By current estimate, the United States generates half of the world's solid and industrial waste. By the year 2000, if present trends continue, the United States will be discarding 192.7 million tons per year. Only about 22% of this waste is projected to be recycled. Landfills are utilized for the disposal of much of this waste. The United States Environmental Protection Agency (EPA) estimates that by the year 2000, 75% of all existing landfills in the United States will be closed.
According to EPA statistics, discarded plastic presently constitutes about 7.3 percent of the U.S. waste stream. Only about 1% of this plastic waste is recycled. By the year 2000, production of plastics in the U.S. is expected to reach 76 billion pounds per year, with discarded plastics expected to make up 10% of the waste stream by weight and up to 1/3 by volume.
There is clearly a pressing need to adopt means by which plastics and other solid waste materials such as wood fiber waste can be recycled into new and useful products. The present invention meets such need.
3. State of the Art Prior to the Present Invention
There have been developed numerous methods for combining waste wood materials and binders. Examples of such methods can be found in the practice of pressboard and extrusion moulding technologies. However, it has been observed that these methods are limited in the raw materials that can be utilized and in the quality and application of the products produced.